1. Field of the Invention
This invention relates to a light-emitting diode (LED) and, more particularly, to an LED capable of preventing a breakdown.
2. Description of the Related Art
A light-emitting diode (LED) is a kind of light-emitting devices capable of directly converting electrical energy to visible light and radiation energy. Since the LED has a series of properties, such as low working voltage, low power consumption, high light-emitting efficiency, small volume and so on, the LED has become a popular product in daily life.
In the LED industrial chain, LED substrates and LED chips are produced in the upstream, the LED chips are designed and manufactured in the midstream, and the LED are encapsulated and tested in the downstream. With popularization of the LED, unprecedented attention is paid to the upstream and midstream industry of the LED, which further advances industrial development of encapsulation technology in the downstream.
The LED encapsulation technology mainly includes lead-type encapsulation and surface mount encapsulation. During the LED lead-type encapsulation, lead frames are used as leads with various kinds of encapsulation appearance. The above encapsulation structure is successfully developed and put on the market at the earliest. There are a great variety of the encapsulation structures, and the technology is in high maturation. The lead-type encapsulation is regarded as the most convenient and economical solution in the current LED encapsulation technology by most customers.
In the lead-type encapsulation, the lead of the LED is combined with a circuit board by wave soldering. When the LED is wave soldered at a high temperature of 270° C., a part of heat is transferred to an encapsulating element via the lead, causing that the temperature at the connecting place of the encapsulating element and the lead reaches 155° C. Since the encapsulating element is mainly made of epoxy, and the upper limit of a heat resisting range thereof is 130+10° C., at that moment, the temperature of the encapsulating element has already been beyond the heat resisting range thereof, causing that properties of the encapsulating element change and the encapsulating element thermally expands, thereby generating great internal stress exceeding bearing pull force of an internal gold wire of the LED. Thus, the gold wire is broken, causing the LED to be broken down.